Since 1981 epizootics of a new primate hepatitis (callitrichid hepatitis (CH) have emerged that produced high mortalities in marmosets and tamarins (Callitrichidae) exhibited in a number of North American zoos and Europe. Our preliminary findings suggest that the cause may be an enveloped virus (CHV) ultrastructurally similar to coronaviridae. We have experimentally transmitted the disease to common marmosets. This strongly suggests that it poses a threat to Callitrichidae housed in primate centers in he U.S. for research use. Although no human disease has been associated with the zoo outbreadks ther is serological evidence from a veterinarian bittn by a naturally infected tamarin that the agent also may have a zoonotic poential. We have detected CHV specific antigen (by Western blots) in livers of the experimentally inoculated marmosets. We will use this material to develop a specific ELISA assay and prepare hyperimmune sera and monoclonal antibodies to CHV antigens. We will determine if CHV is enzootic in the earlier outbreaks, test the prevalence of antibody to CHV in "healthy" callitrichid collections and correlate the hepatitis we have observed with the presence of CHV antigen in material from previous and future epizootics. It is important to learn the host range of this agent to see if it is infectious for other primates (including humans) that then might pass it on to the callitrichids. We will characterize the virus by determining is serological relationships exist between CHV antigens and those of known viruses using standard immunoassays and immunofluorescence. We will explore nucleic acid homology with cloned genomes of other viruses and prepare a cDNA probe to identify CHV-specific nucleic acids in the experimentally infected livers. Also, standard physical and structural properties of the virus will be determined. Attempts to cultivate CHV will be made in primate cells. if successful, susceptible common marmosets will be inoculated to determine whether cell-passaged virus causes disease and can be neurtralized by serum from previously exposed animals.